Multi-effect coupling vacuum continuous desolventizing device and method for preparing calcium d-pantothenate

Abstract

The application discloses a multi-effect coupling vacuum continuous desolventizing device and method for preparing D-calcium pantothenate. The device comprises a first-stage flash tank, a feed preheater connected with the first-stage flash tank, a second-stage flash tank connected with a liquid phase discharge port of the first-stage flash tank, and a crystallization rectifier connected with a liquid phase discharge port of the second-stage flash tank. The device further comprises a deamination tower connected with gas phase discharge ports of the first-stage flash tank, the second-stage flash tank and the crystallization rectifier, a vacuum pump connected with a gas phase discharge port of the deamination tower, an absorption tower connected with a discharge port of the vacuum pump, and a refining tower connected with a discharge port of the absorption tower. The device further comprises an atmospheric tower connected with a liquid phase discharge port of the deamination tower and a high-pressure tower connected with a liquid phase discharge port of the atmospheric tower. The application adopts step-by-step flash evaporation, utilizes different relative volatility of solvents under different pressures to realize separation, and simultaneously utilizes the coupling rectification principle to make gas phase of one tower as a heat source of another tower, thereby achieving the purpose of energy saving.

Description

Technical Field

[0001] This invention relates to a multi-effect coupled vacuum continuous desolvation apparatus and method for preparing D-calcium pantothenate, belonging to the field of D-calcium pantothenate production technology. Background Technology

[0002] D-Calcium pantothenate is a calcium salt of B vitamins. It is an important substance involved in human and animal metabolism and is mainly used in feed additives, food additives, and pharmaceutical raw materials. It is a major component of coenzyme A (CoA). In recent years, my country's biopharmaceutical industry has developed rapidly, and the demand for D-calcium pantothenate has also increased dramatically, resulting in promising domestic and international market prospects and extremely high economic returns.

[0003] Currently, domestic enterprises produce D-calcium pantothenate using two main processes: one involves first obtaining D-pantolytic lactone and then directly obtaining D-calcium pantothenate; the other involves first obtaining D-calcium pantothenate and then inducing its separation. Regardless of the process, methanol and ammonia are required as reaction solvents. The D-calcium pantothenate mother liquor containing methanol and ammonia needs to undergo solvent removal treatment to remove these substances before proceeding to the subsequent crystallization process.

[0004] Currently, the conventional desolventizing process for D-calcium pantothenate mother liquor uses a single-reactor intermittent vacuum desolventizing method. Because D-calcium pantothenate is prone to denaturation at high temperatures, intermittent desolventizing results in a large amount of methanol in the D-calcium pantothenate solution in the bottom of the column, leading to solvent waste. Furthermore, the solvent at the top of the column needs to be removed intermittently, resulting in long operation times, high energy consumption, and the inability to recover ammonia from the top of the column, thus compromising the purity of the methanol at the top. Therefore, finding a desolventizing process that is energy-efficient, environmentally friendly, has a high recovery rate, and produces high-quality products is of great significance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the primary objective of this invention is to provide a multi-effect coupled vacuum continuous desolvation apparatus for preparing D-calcium pantothenate.

[0006] A second objective of the present invention is to provide a method for continuous desolvation using the above-described apparatus.

[0007] To achieve the first objective, the present invention is implemented through the following technical solution: a multi-effect coupled vacuum continuous desolvation device for preparing D-calcium pantothenate, comprising a primary flash tank, a feed preheater connected to the primary flash tank, a secondary flash tank connected to the liquid phase outlet of the primary flash tank, and a crystallizer connected to the liquid phase outlet of the secondary flash tank.

[0008] Preferably, it also includes a deammoniation tower connected to the vapor phase outlet of the primary flash tank, the secondary flash tank, and the crystallizer distillation unit; a vacuum pump connected to the vapor phase outlet of the deammoniation tower; an absorption tower connected to the outlet of the vacuum pump; and a refining tower connected to the liquid phase outlet of the absorption tower.

[0009] Preferably, it also includes an atmospheric pressure tower connected to the liquid phase outlet of the deammoniation tower and a high pressure tower connected to the liquid phase outlet of the atmospheric pressure tower.

[0010] Preferably, the crystallizer is connected to a crystallizer-coupled reboiler, the ammonia removal tower is connected to a ammonia removal tower-coupled reboiler, the ammonia refining tower is connected to an ammonia refining tower reboiler, the atmospheric pressure tower is connected to an atmospheric pressure tower-coupled reboiler, and the high-pressure tower is connected to a high-pressure tower reboiler.

[0011] Preferably, the ammonia removal tower is connected to an ammonia removal tower condenser, the absorption tower is connected to a circulating cooler, and the ammonia refining tower is connected to an ammonia refining tower condenser.

[0012] Preferably, condensate flows between the primary flash tank, the secondary flash tank, the crystallizer distillation unit coupled with the reboiler, the deammoniation tower coupled with the reboiler, the atmospheric tower coupled with the reboiler, and the atmospheric tower and the high-pressure tower.

[0013] Using the above technical solution, the gas phase of the atmospheric distillation tower is divided into three streams: one stream passes through the deammoniation tower coupled with the reboiler, one stream passes through the first-stage flash tank, and one stream passes through the second-stage flash tank. Due to the high temperature of the gas phase, it is condensed after passing through these heat exchangers, and the condensate is then combined. Similarly, the gas phase of the high-pressure tower is divided into two streams: one stream passes through the atmospheric distillation tower reboiler, and one stream passes through the crystallization stripper reboiler. The condensate is then combined after the gas phase is condensed.

[0014] To achieve the second objective, the present invention provides a method for preparing D-calcium pantothenate using a multi-effect coupled vacuum continuous desolvation method, comprising the following steps:

[0015] S1: After the raw material is preheated to 53°C by the feed preheater, it enters the first-stage flash tank for flashing. The unflashed liquid phase enters the second-stage flash tank for flashing again. The unflashed liquid phase enters the crystallization distillation unit for processing to obtain product 1, which is D-calcium pantothenate.

[0016] S2: The gaseous materials (composed of ammonia, methanol, and water) from the top of the primary flash tank, secondary flash tank, and crystallizer distillation unit respectively enter the deammoniation tower for mass transfer separation. The top of the deammoniation tower yields a gaseous material of ammonia, methanol, and water, while the bottom yields a liquid material of methanol and water. The gaseous material is then pumped into the absorption tower via a vacuum pump. The top of the absorption tower contains a gaseous material free of ammonia and methanol, which is discharged into the air. The bottom of the absorption tower contains a liquid material composed of ammonia, methanol, and water, which further enters the ammonia refining tower. The top of the ammonia refining tower yields product 3, which is liquid ammonia. The bottom of the ammonia refining tower contains a mixture of some ammonia, methanol, and water, which is transported to the crystallizer distillation unit to recover some of the ammonia, methanol, and water.

[0017] S3: The liquid material in the bottom of the deammoniation tower first enters the atmospheric pressure tower for separation. Methanol is obtained at the top of the tower, and a mixture of methanol and water is obtained at the bottom. It is then sent to the high pressure tower for recovery. Qualified methanol is obtained at the top of the high pressure tower, and methanol-free wastewater is obtained at the bottom. It is then sent to the crystallization distillation unit to replenish the water in the calcium pantothenate.

[0018] Preferably, the gas phase at the top of the atmospheric pressure column is the heat source for the primary flash tank, the secondary flash tank, and the deammoniation column coupled with the reboiler, and the high pressure column is the heat source for the crystallizer stripper coupled with the reboiler and the atmospheric pressure column coupled with the reboiler.

[0019] Preferably, the reflux ratio of the ammonia removal tower is 30:1, the reflux ratio of the atmospheric pressure tower is 3.2:1, and the reflux ratio of the high pressure tower is 3.2:1.

[0020] Preferably, the raw material in step S1 is a material containing 5% ammonia, 75% methanol, 5% water and 15% D-calcium pantothenate, and the product 1 is 30% D-calcium pantothenate.

[0021] Using the above technical solution, the material containing 5% ammonia, 75% methanol, 5% water, and 15% D-calcium pantothenate is first preheated to 53°C in a feed preheater before entering the first-stage flash tank for negative pressure flash evaporation. Under negative pressure, due to the lower boiling points of ammonia, methanol, and water, some of the ammonia, methanol, and water in the material will flash out in gaseous form. The unflashed liquid phase enters the second-stage flash tank for further flash evaporation of some of the gaseous phase. The first-stage and second-stage flash tanks use jacket heating, and their heat source is the top gaseous phase of the atmospheric pressure tower. The unflashed liquid phase in the second-stage flash tank... The liquid phase enters the crystallizer, which is heated at the bottom by a crystallizer-coupled reboiler. This crystallizer-coupled reboiler is a forced circulation reboiler, which can prevent the crystallizer-coupled reboiler from clogging after the material precipitates. The heat source for the crystallizer-coupled reboiler is the gas phase from the high-pressure tower. In the crystallizer, most of the ammonia and methanol are distilled out, and the bottom is a mixture of water and D-calcium pantothenate. After settling and crystallizing through the bottom settling tube of the crystallizer, a high-concentration D-calcium pantothenate product is obtained and sent to the subsequent crystallization section.

[0022] The three gaseous streams (composed of ammonia, methanol, and water) from the top of the primary flash tank, secondary flash tank, and crystallizer distillation unit respectively enter the deammoniation tower. The bottom of the deammoniation tower is heated by a deammoniation tower coupled reboiler, whose heat source is the gaseous stream from the top of the atmospheric distillation unit. The three streams of ammonia, methanol, and water undergo mass transfer separation in the deammoniation tower, resulting in a gaseous product of ammonia, methanol, and water at the top and a liquid product of methanol and water at the bottom. The reflux ratio of the deammoniation tower is 30:1.

[0023] The gaseous material of ammonia, methanol, and water at the top of the deammoniation tower enters the vacuum pump, thereby maintaining the negative pressure state of the primary flash tank, secondary flash tank, crystallizer, and deammoniation tower. After passing through the vacuum pump, the gaseous material enters the absorption tower. The purpose of the absorption tower is mainly to recover ammonia and methanol from the tail gas. The top of the absorption tower uses deionized water for absorption. The deionized water undergoes mass transfer with the ammonia and methanol gaseous phase in the absorption tower, thereby absorbing the ammonia and methanol into the liquid phase water. The gaseous phase at the top of the absorption tower is a gaseous phase without ammonia and methanol; the bottom is a mixture of ammonia, methanol, and water. This absorption process is an exothermic process, requiring a circulating cooler to circulate and cool it down to 10°C.

[0024] The material in the bottom of the absorption tower is a mixture containing ammonia, methanol, and water. It is sent to the ammonia refining tower, where the purpose is to recover ammonia from the mixture and produce liquid ammonia for subsequent production. The bottom of the ammonia refining tower is heated by the ammonia refining tower reboiler, which uses low-pressure steam as its heat source. Liquid ammonia is obtained at the top of the ammonia refining tower, while a mixture containing some ammonia, methanol, and water is obtained at the bottom. The bottom material is sent to the crystallization stripper to recover some of the ammonia, methanol, and water.

[0025] The liquid material from the bottom of the deammoniation tower first enters the atmospheric pressure tower. The purpose of the atmospheric pressure tower is to obtain a high concentration of methanol product at the top. The atmospheric pressure tower is heated by an atmospheric pressure tower coupled with a reboiler, and its heat source is the top gas phase of the high-pressure tower. The top gas phase of the atmospheric pressure tower serves as a heat source for the preceding equipment. The material containing methanol and water is separated in the atmospheric pressure tower. Methanol is obtained at the top of the tower, and the bottom of the tower contains a mixture of methanol and water, which is subsequently sent to the high-pressure tower for recovery. The atmospheric pressure tower operates at atmospheric pressure, and the reflux ratio of the atmospheric pressure tower is 3.2:1.

[0026] The purpose of the high-pressure tower is to recover methanol. The high-pressure tower operates under pressure. After separation in the tower, qualified methanol is obtained at the top of the tower, and methanol-free wastewater is obtained at the bottom of the tower. The methanol-free wastewater is sent to the crystallization distillation unit to replenish the water in D-calcium pantothenate. The high-pressure tower is heated by a high-pressure tower reboiler, and the heat source for the high-pressure tower reboiler is low-pressure steam. The reflux ratio of the high-pressure tower is 3.2:1.

[0027] The primary and secondary flash tanks are equipped with demisters; the crystallizers, ammonia stripping towers, absorption towers, atmospheric distillation towers, and high-pressure towers are equipped with packing materials and internal components.

[0028] The beneficial effects of this invention are:

[0029] (1) The present invention adopts step-by-step flash evaporation, which utilizes the different relative volatility of solvents under different pressures to achieve separation. At the same time, it utilizes the principle of coupled distillation to make the gas phase of one column the heat source of another column, thereby achieving the purpose of energy saving.

[0030] (2) The method provided by the present invention is stable in operation and has conventional and reasonable processing parameters. It can improve product quality indicators and make full use of thermal energy and reduce operating energy.

[0031] (3) The present invention is a three-effect coupled distillation, which consists of one (or more) high-temperature column, medium-temperature column and low-temperature column; the high-temperature gas phase at the top of the high-temperature column serves as the heat source for the reboiler at the bottom of the medium-temperature column, and the high-temperature gas phase at the top of the medium-temperature column serves as the heat source for the reboiler at the bottom of the low-temperature column, thereby simultaneously realizing the condensation of the gas phase at the top of the high-temperature column and the heating of the liquid phase at the bottom of the medium-temperature column, and the condensation of the gas phase at the top of the medium-temperature column and the heating of the liquid phase at the bottom of the low-temperature column, effectively reducing the consumption of high-temperature heat source and low-temperature cold source. Attached Figure Description

[0032] Figure 1 This is a process flow diagram of a multi-effect coupled vacuum continuous desolvation method according to the present invention.

[0033] In the diagram: 1-First-stage flash tank, 2-Second-stage flash tank, 3-Crystallizing distillation unit, 4-Ammonia removal tower, 5-Absorber, 6-Ammonia refining tower, 7-Ambient pressure tower, 8-High pressure tower, 9-Feed preheater, 10-Crystallizing distillation unit coupled with reboiler, 11-Ammonia removal tower condenser, 12-Ammonia removal tower coupled with reboiler, 13-Vacuum pump, 14-Circulating cooler, 15-Ammonia refining tower condenser, 16-Ammonia refining tower reboiler, 17-Ambient pressure tower coupled with reboiler, 18-High pressure tower reboiler;

[0034] Product 1 - D-calcium pantothenate, Product 2 - methanol, Product 3 - liquid ammonia. Detailed Implementation

[0035] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0036] Example 1

[0037] like Figure 1 As shown, the multi-effect coupled vacuum continuous desolvation device for preparing D-calcium pantothenate includes a primary flash tank 1, a feed preheater 9 connected to the primary flash tank 1, a secondary flash tank 2 connected to the liquid phase outlet of the primary flash tank 1, and a crystallizer distiller 3 connected to the liquid phase outlet of the secondary flash tank 2.

[0038] In this embodiment, it also includes a deammoniation tower 4 connected to the gas phase outlet of the primary flash tank 1, the secondary flash tank 2, and the crystallizer distillation unit 3; a vacuum pump 13 connected to the gas phase outlet of the deammoniation tower 4; an absorption tower 5 connected to the outlet of the vacuum pump 13; and a refining tower 6 connected to the outlet of the absorption tower 5.

[0039] In this embodiment, it also includes an atmospheric pressure tower 7 connected to the liquid phase outlet of the deammoniation tower 4 and a high pressure tower 8 connected to the liquid phase outlet of the atmospheric pressure tower 7.

[0040] In this embodiment, the crystallizer distiller 3 is connected to the crystallizer distiller coupled with the reboiler 10, the ammonia removal tower 4 is connected to the ammonia removal tower coupled with the reboiler 12, the ammonia refining tower 6 is connected to the ammonia refining tower reboiler 16, the atmospheric tower 7 is connected to the atmospheric tower coupled with the reboiler 17, and the high-pressure tower 8 is connected to the high-pressure tower reboiler 18.

[0041] In this embodiment, the ammonia removal tower 4 is connected to the ammonia removal tower condenser 11, the absorption tower 5 is connected to the circulating cooler 14, and the ammonia refining tower 6 is connected to the ammonia refining tower condenser 15.

[0042] In this embodiment, condensate flows between the primary flash tank 1, the secondary flash tank 2, the feed preheater 9, the crystallizer distillation unit coupled with the reboiler 10, the deammoniation tower coupled with the reboiler 12, the atmospheric tower coupled with the reboiler 17, the atmospheric tower 7, and the high-pressure tower 8.

[0043] Example 2

[0044] A multi-effect coupled vacuum continuous solvent removal method for preparing D-calcium pantothenate includes the following steps:

[0045] S1: After the raw material is preheated to 53°C by the preheater 9, it enters the first-stage flash tank 1 for flashing. The unflashed liquid phase enters the second-stage flash tank 2 for flashing again. The unflashed liquid phase enters the crystallization distillation unit 3 for processing to obtain product 1, which is D-calcium pantothenate.

[0046] Specifically, a material containing 5% ammonia, 75% methanol, 5% water, and 15% D-calcium pantothenate is first preheated to 53°C in a feed preheater 9 at a flow rate of 1000 kg / h before entering the first-stage flash tank 1 under negative pressure (70 kPaA, 57°C) for flash evaporation. Under negative pressure, due to the lower boiling points of ammonia, methanol, and water, some of the ammonia, methanol, and water in the material will flash out in gaseous form. The unflashed liquid phase enters the second-stage flash tank 2 (pressure 60 kPaA, 56°C) for further flash evaporation of some of the gaseous phase. The first-stage flash tank 1 and the second-stage flash tank 2 use jacket heating, with the heat source being the top gas phase of the atmospheric pressure tower 7. The unflashed liquid phase in the second-stage flash tank 2... The liquid phase enters the crystallizer distiller 3. The bottom of the crystallizer distiller 3 is heated by the crystallizer distiller coupled with a reboiler 10. This crystallizer distiller coupled with a reboiler 10 is a forced circulation reboiler, which can prevent the crystallizer distiller coupled with a reboiler 10 from clogging after the material precipitates. The heat source of the crystallizer distiller coupled with a reboiler 10 is the gas phase of the high-pressure tower 18. In the crystallizer distiller 3, most of the ammonia and methanol are distilled out. The bottom is a mixture of water and D-calcium pantothenate. After sedimentation and crystallization through the bottom settling tube of the crystallizer distiller 3, a high concentration of D-calcium pantothenate product (methanol content less than 200ppm, flow rate 475kg / h) is obtained and sent to the subsequent crystallization section.

[0047] S2: The gaseous materials (composed of ammonia, methanol, and water) at the top of the primary flash tank 1, secondary flash tank 2, and crystallizer distillation unit 3 respectively enter the ammonia removal tower 4 for mass transfer separation. The top of the ammonia removal tower 4 yields a gaseous material of ammonia, methanol, and water, while the bottom yields a liquid material of methanol and water. The gaseous material enters the absorption tower 5 through the vacuum pump 13. The top of the absorption tower 5 contains a gaseous material without ammonia and methanol, which is discharged into the air. The bottom of the absorption tower 5 contains a liquid material composed of ammonia, methanol, and water, which further enters the ammonia refining tower 6. The top of the ammonia refining tower 6 yields product 3, which is liquid ammonia. The bottom of the ammonia refining tower 6 contains a mixture of some ammonia, methanol, and water, which is transported to the crystallizer distillation unit 3 to recover some ammonia, methanol, and water.

[0048] Specifically, the three gaseous streams (composed of ammonia, methanol, and water) from the top of the primary flash tank 1, secondary flash tank 2, and crystallizer stripper 3 respectively enter the deammoniation tower 4. The bottom of the deammoniation tower 4 is heated by the deammoniation tower coupled reboiler 12, whose heat source is the gaseous stream from the top of the atmospheric pressure tower 7. The three materials, ammonia, methanol, and water, undergo mass transfer separation in the deammoniation tower 4, resulting in a gaseous material of ammonia, methanol, and water at the top and a liquid material of methanol and water at the bottom. The reflux ratio of the deammoniation tower 4 is 30:1.

[0049] The gaseous material of ammonia, methanol, and water at the top of the deammoniation tower 4 enters the vacuum pump 13, thereby maintaining the negative pressure state of the primary flash tank 1, secondary flash tank 2, crystallizer distiller 3, and deammoniation tower 4. After passing through the vacuum pump 13, the gaseous material enters the absorption tower 5. The main purpose of the absorption tower 5 is to recover ammonia and methanol from the tail gas. The top of the absorption tower 5 uses deionized water for absorption. The deionized water undergoes mass transfer with the ammonia and methanol gaseous phase in the absorption tower, thereby absorbing the ammonia and methanol into the liquid phase water. The gaseous phase at the top of the absorption tower 5 is a gaseous phase without ammonia and methanol; the bottom is a mixture of ammonia, methanol, and water. This absorption process is an exothermic process, which requires the circulating cooler 14 to circulate and cool it down to 10°C.

[0050] The material in the bottom of the absorption tower 5 is a mixture containing ammonia, methanol, and water, which is sent to the ammonia refining tower 6. The purpose of the ammonia refining tower 6 is to recover the ammonia in the mixture and produce liquid ammonia for subsequent production. The bottom of the ammonia refining tower 6 is heated by the ammonia refining tower reboiler 15. The heat source of the ammonia refining tower reboiler 15 is low-pressure steam (1.0 MPaG). Liquid ammonia is obtained at the top of the ammonia refining tower 6, and a mixture containing some ammonia, methanol, and water is obtained in the bottom of the tower. The bottom material is sent to the crystallization stripper 3 to recover some ammonia, methanol, and water.

[0051] S3: The liquid material in the bottom of the deammoniation tower 4 first enters the atmospheric pressure tower 7 for separation. The top of the tower yields methanol, and the bottom of the tower yields a mixture of methanol and water. It is then sent to the high pressure tower 8 for recovery. The top of the tower yields qualified methanol, and the bottom of the tower yields methanol-free wastewater. It is then further sent to the crystallization distillation unit 3 to replenish the water in the calcium pantothenate.

[0052] Specifically, the liquid material from the bottom of the deammoniation tower 4 first enters the atmospheric tower 7. The purpose of the atmospheric tower 7 is to obtain a high concentration of methanol product at the top of the tower. The atmospheric tower 7 is heated by the atmospheric tower coupled reboiler 17, and its heat source is the top gas phase of the high-pressure tower 8. The top gas phase of the atmospheric tower 8 serves as a heat source for the preceding equipment. The material containing methanol and water is separated in the atmospheric tower 7. Methanol is obtained at the top of the tower, and the bottom of the tower contains a mixture of methanol and water, which is subsequently sent to the high-pressure tower 8 for recovery. The atmospheric tower 7 operates at atmospheric pressure. The reflux ratio of the atmospheric tower 7 is 3.2:1.

[0053] The purpose of high-pressure tower 8 is to recover methanol. High-pressure tower 8 operates under pressure. After separation in the tower, qualified methanol is obtained at the top of the tower, and methanol-free wastewater is obtained at the bottom of the tower. The methanol-free wastewater is sent to crystallizer 3 to replenish the water in D-calcium pantothenate. High-pressure tower 8 is heated by high-pressure tower reboiler 18. The heat source of high-pressure tower reboiler 18 is low-pressure steam (1.0 MPaG). The reflux ratio of high-pressure tower 8 is 3.2:1.

[0054] The primary flash tank 1 and the secondary flash tank 2 are equipped with demisters; the crystallizer distillation unit 3, the ammonia stripping tower 4, the absorption tower 5, the atmospheric pressure tower 7, and the high pressure tower 8 are equipped with packing and internal components.

[0055] This invention is a triple-effect coupled distillation, where triple-effect means that it consists of one (or more) high-temperature column, medium-temperature column, and low-temperature column. The high-temperature gas phase at the top of the high-temperature column serves as the heat source for the reboiler at the bottom of the medium-temperature column, and the high-temperature gas phase at the top of the medium-temperature column serves as the heat source for the reboiler at the bottom of the low-temperature column. This simultaneously achieves the condensation of the gas phase at the top of the high-temperature column and the heating of the liquid phase at the bottom of the medium-temperature column, as well as the condensation of the gas phase at the top of the medium-temperature column and the heating of the liquid phase at the bottom of the low-temperature column, effectively reducing the consumption of high-temperature heat source and low-temperature cold source.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0057] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A multi-effect coupled vacuum continuous desolvation apparatus for preparing D-calcium pantothenate, characterized in that, It includes a primary flash tank (1), a feed preheater (9) connected to the primary flash tank (1), a secondary flash tank (2) connected to the liquid phase outlet of the primary flash tank (1), and a crystallizer (3) connected to the liquid phase outlet of the secondary flash tank (2), a deammoniation tower (4) connected to the gas phase outlets of the primary flash tank (1), the secondary flash tank (2), and the crystallizer (3), a vacuum pump (13) connected to the gas phase outlet of the deammoniation tower (4), an absorption tower (5) connected to the outlet of the vacuum pump (13), an ammonia refining tower (6) connected to the liquid phase outlet of the absorption tower (5), an atmospheric tower (7) connected to the liquid phase outlet of the deammoniation tower (4), and a high-pressure tower (8) connected to the liquid phase outlet of the atmospheric tower (7).

2. The multi-effect coupled vacuum continuous desolvation apparatus for preparing D-calcium pantothenate as described in claim 1, characterized in that, The crystallizer (3) is connected to a crystallizer coupled reboiler (10), the deammoniation tower (4) is connected to a deammoniation tower coupled reboiler (12), the ammonia refining tower (6) is connected to an ammonia refining tower reboiler (16), the atmospheric tower (7) is connected to an atmospheric tower coupled reboiler (17), and the high-pressure tower (8) is connected to a high-pressure tower reboiler (18).

3. The multi-effect coupled vacuum continuous desolvation apparatus for preparing D-calcium pantothenate as described in claim 2, characterized in that, The ammonia removal tower (4) is connected to an ammonia removal tower condenser (11), the absorption tower (5) is connected to a circulating cooler (14), and the ammonia refining tower (6) is connected to an ammonia refining tower condenser (15).

4. The multi-effect coupled vacuum continuous desolvation apparatus for preparing D-calcium pantothenate as described in claim 3, characterized in that, The condensate flows between the primary flash tank (1), the secondary flash tank (2), the crystallizer distillation coupled reboiler (10), the deammoniation tower coupled reboiler (12), the atmospheric tower coupled reboiler (17), the atmospheric tower (7), and the high-pressure tower (8).

5. A method for desolvation using the apparatus according to any one of claims 1-4, characterized in that, Includes the following steps: S1: After the raw material is preheated to 53°C by the feed preheater (9), it enters the first-stage flash tank (1) for flashing. The unflashed liquid phase enters the second-stage flash tank (2) for flashing again. The unflashed liquid phase enters the crystallizer (3) for processing to obtain product 1, which is D-calcium pantothenate. S2: The gaseous materials at the top of the primary flash tank (1), the secondary flash tank (2), and the crystallizer (3) are respectively fed into the deammoniation tower (4) for mass transfer separation. The top of the deammoniation tower (4) yields a gaseous material of ammonia, methanol, and water, and the bottom of the deammoniation tower (4) yields a liquid material of methanol and water. The gaseous material is fed into the absorption tower (5) by the vacuum pump (13). The top of the absorption tower (5) is a gaseous material without ammonia and methanol, which is discharged into the air. The bottom of the absorption tower (5) is a liquid phase composed of ammonia, methanol, and water, which is further fed into the ammonia refining tower (6). The top of the ammonia refining tower (6) yields product 3, which is liquid ammonia. The bottom of the ammonia refining tower (6) is a mixture containing some ammonia, methanol, and water, which is transported to the crystallizer (3) to recover some ammonia, methanol, and water. S3: The liquid material in the bottom of the deammoniation tower (4) first enters the atmospheric pressure tower (7) for separation. The top of the tower is methanol, and the bottom of the tower is a mixture of methanol and water. It is then sent to the high pressure tower (8) for recovery. The top of the tower is qualified methanol, and the bottom of the tower is methanol-free wastewater. It is then sent to the crystallizer (3) to replenish the water in the calcium pantothenate.

6. The method for preparing D-calcium pantothenate using a multi-effect coupled vacuum continuous desolvation process as described in claim 5, characterized in that, The gas phase at the top of the atmospheric pressure tower (7) is the heat source for the primary flash tank (1), the secondary flash tank (2), and the deammoniation tower coupled reboiler (12), while the gas phase of the high pressure tower (8) is the heat source for the crystallizer distiller coupled reboiler (10) and the atmospheric pressure tower coupled reboiler (17).

7. The method for preparing D-calcium pantothenate using a multi-effect coupled vacuum continuous desolvation process as described in claim 6, characterized in that, The reflux ratio of the ammonia removal tower (4) is 30:1, the reflux ratio of the atmospheric tower (7) is 3.2:1, and the reflux ratio of the high-pressure tower (8) is 3.2:

1.

8. The method for preparing D-calcium pantothenate using a multi-effect coupled vacuum continuous desolvation process as described in claim 7, characterized in that, The raw material in step S1 is a material containing 5% ammonia, 75% methanol, 5% water and 15% D-calcium pantothenate, and its product 1 is 30% D-calcium pantothenate.

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